Petroleum Microbiology Research Group, Department of Biological Sciences, University, of Calgary, Calgary, Alberta, Canada.
Appl Environ Microbiol. 2013 Aug;79(16):5059-68. doi: 10.1128/AEM.01251-13. Epub 2013 Jun 14.
Oil production by water injection can cause souring in which sulfate in the injection water is reduced to sulfide by resident sulfate-reducing bacteria (SRB). Sulfate (2 mM) in medium injected at a rate of 1 pore volume per day into upflow bioreactors containing residual heavy oil from the Medicine Hat Glauconitic C field was nearly completely reduced to sulfide, and this was associated with the generation of 3 to 4 mM acetate. Inclusion of 4 mM nitrate inhibited souring for 60 days, after which complete sulfate reduction and associated acetate production were once again observed. Sulfate reduction was permanently inhibited when 100 mM nitrate was injected by the nitrite formed under these conditions. Pulsed injection of 4 or 100 mM nitrate inhibited sulfate reduction temporarily. Sulfate reduction resumed once nitrate injection was stopped and was associated with the production of acetate in all cases. The stoichiometry of acetate formation (3 to 4 mM formed per 2 mM sulfate reduced) is consistent with a mechanism in which oil alkanes and water are metabolized to acetate and hydrogen by fermentative and syntrophic bacteria (K. Zengler et al., Nature 401:266-269, 1999), with the hydrogen being used by SRB to reduce sulfate to sulfide. In support of this model, microbial community analyses by pyrosequencing indicated SRB of the genus Desulfovibrio, which use hydrogen but not acetate as an electron donor for sulfate reduction, to be a major community component. The model explains the high concentrations of acetate that are sometimes found in waters produced from water-injected oil fields.
注水采油会导致酸化，注入水中的硫酸盐被原地硫酸盐还原菌（SRB）还原为硫化物。以每天 1 个孔隙体积的速度注入含有马格尼托哥尔斯克褐煤型油藏残留重油的上流生物反应器中的培养基中，硫酸盐（2 mM）几乎完全被还原为硫化物，同时产生了 3 到 4 mM 的乙酸盐。包含 4 mM 硝酸盐的情况下，抑制酸化可持续 60 天，之后再次观察到完全的硫酸盐还原和相关的乙酸盐生成。当以硝酸盐形式注入 100 mM 硝酸盐时，由于这些条件下形成的亚硝酸盐，硫酸盐还原被永久抑制。以硝酸盐形式脉冲式注入 4 或 100 mM 硝酸盐可暂时抑制硫酸盐还原。一旦停止硝酸盐注射，硫酸盐还原就会恢复，并在所有情况下都伴随着乙酸盐的生成。乙酸盐形成的化学计量（每还原 2 mM 硫酸盐形成 3 到 4 mM）与一种机制一致，即在这种机制中，油烷烃和水被发酵和共生细菌代谢为乙酸盐和氢气（K. Zengler 等人，《自然》401:266-269, 1999），其中氢气被 SRB 用于将硫酸盐还原为硫化物。为了支持这一模型，焦磷酸测序的微生物群落分析表明，Desulfovibrio 属的 SRB 是主要的群落组成部分，该菌使用氢气而不是乙酸盐作为硫酸盐还原的电子供体。该模型解释了有时在注水油田采出水中发现的高浓度乙酸盐的原因。
